Petrified Forest National Park - Painted Desert - Photos

Petrified Forest National Park - Painted Desert - Wildlife

Animal life at Petrified Forest includes amphibians, birds, insects, spiders, mammals, and reptiles. Birds, lizards and rabbits are seen most frequently, though seasons and weather play a large role in determining what animals are active.

For many animals, activity occurs during a particular temperature range. "Crepuscular" animals are active at dawn and dusk, the coolest times of day. The half-darkness makes prey animals less visible, yet visibility is good enough to locate food.

Activity can change with the season, too. Snakes and lizards are "diurnal" (active during the day) in late spring and early fall, but they become "crepuscular" (active at dawn and dusk) during the heat of summer.

Many animals in the park are "nocturnal" (active at night). This is an adaptation not only to avoid high summer daytime temperatures, but also to avoid certain predators.

You are much more likely to see animal life in the park if you come as early as park hours allow and stay as late as allowed. These are also the times when the angle of the sun makes the views and colors of the Painted Desert most spectacular.

Whenever you are in a national park, do not approach, feed, or harass any wildlife. Help your parks reduce the impact of human visitors to the homeland of many wild species.

BIRDS

Like many national park areas, Petrified Forest National Park provides a unique place of protection and preservation. Here, birds can find food and shelter that may not be available in other regions on their journeys from habitat to habitat. Patches of healthy, undeveloped habitats are found in the modern fragmented landscape, connected by corridors such as Petrified Forest National Park.

Petrified Forest has a variety of habitats. Raptors, songbirds, and ground birds can be found in the grassland. Riparian corridors provide food and shelter for warblers, vireos, avocets, killdeer, and others. The exotic and native trees and shrubs around the Visitor Center and Rainbow Forest Museum provide home for western tanagers, hermit warblers, and house finches. The park also offers sightings of vagrant shore birds and rare Eastern birds not seen often in Arizona. Rarities, such as black-throated blue warbler, have been found by Maricopa Audubon Society members. September and early October seem to be the best time to visit the area to see these fascinating vagrants.

Like the canary in the mine, birds gauge the health and safety of our environment. By watching birds, noting species, and the migration of species, we can understand the changes in our environment.

REPTILES

Well adapted to the often dry environment of Petrified Forest National Park, reptiles play an important part in maintaining the health of the ecosystem. Over sixteen varieties of lizards and snakes make Petrified Forest their home. Reptiles occupy a variety of habitats ranging from grassland to rocky slopes. They consume large quantities of insects, spiders, scorpions, other reptiles and small mammals thereby preventing infestations of any single species. Respecting the entire reptile community helps to preserve this vital link.

All reptiles are "ectothermic," or cold-blooded, regulating body temperature via external sources rather than internal metabolism. The metabolic rate of a reptile is very low, but so are its energy needs. Keeping warm in the Arizona sunshine does not require much work, so energy generated can be used for reproduction and finding food instead of for heating and cooling. Of course, there are limitations to this type of adaptation. Since they cannot pant or sweat, reptiles are not able to endure extremely high temperatures without shade. They also cannot endure freezing temperatures. When it is cold, they hibernate or enter into an inactive torpor.

When lizards are seen scurrying across a rock or path, please resist the urge to catch them. Lizards can have a mean bite and some will actually shed a tail to escape capture. Though the tail will grow back, a great deal of body energy is used in the process and population dynamics will be affected. Enjoy them from a respectful distance.

The following is a list of the reptiles known to occur in the park. Help protect this important park ecosystem by observing our reptile inhabitants from a distance.

AMPHIBIANS

Well adapted to the often dry environment of Petrified Forest National Park, reptiles play an important part in maintaining the health of the ecosystem. Over sixteen varieties of lizards and snakes make Petrified Forest their home. Reptiles occupy a variety of habitats ranging from grassland to rocky slopes. They consume large quantities of insects, spiders, scorpions, other reptiles and small mammals thereby preventing infestations of any single species. Respecting the entire reptile community helps to preserve this vital link.

All reptiles are "ectothermic," or cold-blooded, regulating body temperature via external sources rather than internal metabolism. The metabolic rate of a reptile is very low, but so are its energy needs. Keeping warm in the Arizona sunshine does not require much work, so energy generated can be used for reproduction and finding food instead of for heating and cooling. Of course, there are limitations to this type of adaptation. Since they cannot pant or sweat, reptiles are not able to endure extremely high temperatures without shade. They also cannot endure freezing temperatures. When it is cold, they hibernate or enter into an inactive torpor.

When lizards are seen scurrying across a rock or path, please resist the urge to catch them. Lizards can have a mean bite and some will actually shed a tail to escape capture. Though the tail will grow back, a great deal of body energy is used in the process and population dynamics will be affected. Enjoy them from a respectful distance.

The following is a list of the reptiles known to occur in the park. Help protect this important park ecosystem by observing our reptile inhabitants from a distance.

Can you imagine living underground for nine months of the year and not eating, drinking, or defecating? Amphibians are an amazing group of animals do just that.

It is hard to imagine that in this dry region animals that require consistent moisture could thrive. Three hundred and fifty million years ago the first fish-like amphibian hauled itself out of the sea. Within the sedimentary rock of the park, giant amphibians such as metoposaurs have been discovered as fossils. By the time dinosaurs appeared, amphibians were flourishing. Today, they are still among the most successful groups of animals.

Why have they survived and adapted to such varied environments worldwide? Permeable skin! Amphibians do not drink; they absorb water through their skin. Spadefoot toads, residents of the park, absorb water from the soil in which they hibernate. Although permeable skin allows for water absorption, it provides little barrier to evaporation. This causes the animal's water balance to be in constant flux. Evaporative water loss also results in loss of body temperature. This is why you often see amphibians on warm pavement in the evening. It is not an easy life for amphibians in this dry grassland. Behavioral and physiological mechanisms that shape their daily life make it possible for them to survive.

Although amphibians have survived here for millions of years, today they are in trouble. Biologists around the world have noted dramatic declines in amphibian populations. No one knows what is causing these declines, but it is thought to be a sign of unfavorable environmental changes. Habitats such as wetlands are being destroyed, pesticides and metal poisons are contaminating the water, new predators are being introduced, the ozone layer is being depleted, and global climate changes are underway. In some cases, natural population fluctuations may explain the decline but scientists have ruled out natural causes as the only explanation for the overall problem. All around the world, declines are occurring in many species. What is clear is that human actions are the primary cause of these declines.

The following is a list of amphibians known to currently occur in the park. Further research will undoubtedly locate more species as different habitats in the park are more thoroughly studied.

Mammals are a diverse group of animals, ranging from the delicate white-footed mouse to the elegant mule deer. Mammals have fur or hair, produce milk for their offspring, and are warm-blooded.

In the often extreme climate of the plateau country, animals use such survival strategies as hiding in their burrows or migration as well as physiological adaptations like hollow hairs for insulation. Many animals in arid regions are nocturnal, using the cooler night to survive the heat of summer or the darkness of the late hours to escape notice of predators.

Early morning is the best time to view mammals while in the park. Do not approach, feed, or harass any wildlife in Petrified Forest or any other national park area.

The list below features only a few of the many species of mammals in the park.

Petrified Forest National Park - Painted Desert - Ecology

Not all plants at Petrified Forest National Park are fossils. Living plants are critical components within the grassland ecosystem found throughout the park. Plants capture particulate dust in the air, filter gaseous pollutants, convert carbon dioxide to oxygen, provide habitat for animals, and supply raw materials for humans.

Plants of arid climates have adaptations which enable them to survive the extremes of temperature and precipitation. These adaptations can be grouped in two basic categories, drought escapers and drought resistors. Drought escapers are plants which take advantage of favorable growing conditions when they exist, but go dormant when those conditions disappear. They are usually annuals, growing only when enough water is available.

Seeds produced under good conditions can lie dormant for years if conditions are not favorable for germination. Most grasses and wildflowers are drought escapers. Drought resistors are typically perennials. They have mechanisms for reducing the damage a drought can cause. For example, some will drop their leaves if water is unavailable. Many have small, hairy leaves which reduce exposure to air currents and solar radiation and thereby limit the amount of water lost to evaporation. Cacti, yuccas and mosses are examples of drought resistors. Yuccas have extensive taproots which can reach water beyond the ability of other plants. Mosses can tolerate complete dehydration. When rains return after extensive dry periods, mosses green up immediately

GRASSES

Grasses are one of the most important plants within the grassland ecosystem found in the park. Large expanses of grasslands form where wind-blown sediment and erosion have created a layer of soil several feet thick. One of the most devastating causes of grassland destruction is grazing by cattle and horses. Because grazing is not allowed within the park, the area has returned to a more natural state and is one of the largest recovering grasslands in the Southwest.

Individual grasses sprout almost anywhere they can find soil, even in potholes filled with dirt. Most grasses fit into two basic groups, bunch grass and sod-forming grass. Bunch grass is classic arid adapted grass occurring in scattered clumps. Its spreading growth pattern reduces competition for limited soil nutrients and water. Examples of bunch grass include rice grass and needle-and-thread grass. The large rice grass seeds are rich in protein and were an important source of food for American Indians. Needle-and-thread grass has a sharp seed attached to a thin thread-like tail which develops in a spiral, wound fashion. As the thread unwinds, it drives the seed into the ground. Both of these grasses are perennial, becoming dormant during droughts. Rice grass plants have been known to live over 100 years, through wet and dry times.

Sod-forming grass is what most people have in their yards. Galleta and Blue Grama, sod-forming perennials native to Petrified Forest National Park, usually grow together. Cheat grass was accidentally brought to the United States in the 1800s and is now found throughout the park.

To visitors unaccustomed to the vast landscapes of the Southwest, Petrified Forest National Park can seem somewhat barren. On closer look, the land is teeming with interesting and clever life.

LICHENS

In many areas of Petrified Forest National Park, large collections of exposed rock surfaces are covered by lichens, especially the shaded north side. A lichen is actually a simple community of at least two mutually-dependent organisms: fungi and green algae. When both organisms are dependent on the other, they are said to be symbiotic. Green algae uses the photosynthesis process to produce food for the fungus, while the fungus protects the algae from the elements and extracts nutrients from soil and rock. The lichen structure is more elaborate and durable than either fungus or algae alone.

Lichens are well adapted to arid climates. They can continue food production at any temperature above freezing. Lichens can absorb more than their own weight of water and can absorb emphemeral water, such as dew, almost directly into their cells. The water does not need to go through roots and stems as it does in vascular plants.

Many other plants benefit from the presence of lichens. The green algae component of lichens can transform nitrogen in the air, which is unusable to most organisms, into a form which is essential for life. This is especially important in arid climates where lack of nitrogen is known to limit productivity.

Because lichens take everything they need from the air, they are dependent on good air quality. Scientists turn to lichens as indicators of air quality. It is truly amazing how nature, over time, can establish symbiotic relationships for the benefit of the whole ecosystem.

WILDFLOWERS

Wildflowers have adapted to the arid climate at Petrified Forest National Park in many different ways. Thick, waxy coverings on leaves and stems reduce evaporation. Small leaves reduce the effects of solar radiation and water loss. Deep taproots reach far into the soil to find water while shallow, widespread roots catch and absorb surface water quickly. Despite these adaptations, wildflowers avoid drought and heat by hiding in the soil as seeds or bulbs, sometimes for decades. Germination only occurs after significant seasonal rainfall.

While most wildflowers bloom during the day, some take advantage of cooler night temperatures to open their flowers. Evening-blooming plants include evening primrose, sacred datura, sand verbena, and yucca. The yucca and the yucca moth have a fascinating dependency on one another which includes trysts in the night. After mating, the female moth gathers pollen from a yucca flower and packs it into a ball. She then flies into the night until locating another yucca flower.

Here she lays eggs in the base of the flower's pistil and packs pollen from her pollen ball down into the pistil, providing food for her young when they hatch. She visits several flowers during the night, each time distributing the pollen from flower to flower. Thus she fertilizes the yucca flowers while ensuring that her young will have nutrients to live on. Yucca plants and moths have a symbiotic relationship: yucca flowers are only pollinated by yucca moths and yucca moth larvae only feed on yucca pollen.

April and May, following winter snow and rain, are generally the best months to see wildflowers throughout the Southwest. Beginning in late August, if the summer monsoon season (July-August) has brought significant rainfall, different species bloom and color the landscape once again.

Petrified Forest National Park - Painted Desert - Geology

Erosion has sculpted and shaped intriguing landforms. The rocks reveal an enthralling chronicle of time that is unfolding and ever-changing. What can the rocks tell us? Think of the colorful layers as pages in a massive book. As the pages are turned, we discover that the words are a language we do not completely understand. The pictures help, but we must put together the story of this ancient book with fragmented clues. The first chapter of this geological text is the Chinle Formation.

Chinle Formation

The colorful badland hills, flat-topped mesas, and sculptured buttes of the Painted Desert are primarily made up of the Chinle Formation, mainly fluvial (river related) deposits. Within Petrified Forest National Park, the layers of the Chinle Formation include the Blue Mesa Member, the Sonsela Member, the Petrified Forest Member, and the Owl Rock Member.

The Blue Mesa Member consists of thick deposits of grey, blue, purple, and green mudstones and minor sandstone beds, the most prominent of which is the Newspaper Rock Sandstone. This unit is best exposed in the Tepees area of the park. The Blue Mesa Member is approximately 220-225 million years old.

The Sonsela Member is divided into three parts: 1) the upper Flattops One Bed, which consists of a thick cliff-forming brown, cross-bedded sandstone, 2) the middle Jim Camp Wash Beds of blue, grey, and purple mudstones and numerous small grey and white sandstone beds, and 3) the lower Rainbow Forest bed consisting of white cross-bedded sandstone and conglomerate of rounded pebbles and cobbles which contains the logs of the Rainbow Forest. This sandstone caps Blue Mesa, Agate Mesa, and the mesa north of the Rainbow Forest. The Sonsela Member is approximately 216 million years old.

The Petrified Forest Member consists of thick sequences of reddish mudstones and brown sandstone layers. This member is exposed in the Flattops and is the white and pink reworked volcaniclastic unit of the Painted Desert. It contains large amounts of petrified wood. The Black Forest Bed, part of the Petrified Forest Member north of Kachina Point, has been dated isotopically at 213 +/- 1.7 million years old.

The Owl Rock Member consists of pinkish-orange mudstones mixed with hard, thin layers of limestone. Lenses of selenite gypsum are scattered periodically throughout the Owl Rock Member representing the minerals left behind after evaporation of inland lakes. This member is exposed on Chinde Mesa at the northernmost border of the park. The Owl Rock Member is approximately 205 million years old.

The colorful layers in the Chinle Formation represent ancient soil horizons. The coloration is due to the presence of various minerals. While the red and green layers generally contain the same amount of iron and manganese, differences in color depend on the position of the groundwater table when the ancient soils were formed. In soils where the water table was high, a reducing environment existed due to a lack of oxygen in the sediments, giving the iron minerals in the soil a greenish or bluish hue. The reddish soils were formed where the water table fluctuated, allowing the iron minerals to oxidize (rust).
Bidahochi Formation

During the Late Miocene and Early Pliocene Epochs of the Neogene Period (4-8 million years ago) a large lake basin with ephemeral lakes covered much of Northeastern Arizona. Fine-grained fluvial and lacustrine (lake related) sediment such as silt, clay, and sand represent the lower part of the Bidahochi Formation. Volcanoes, both nearby and as far as the Southwestern Nevada Volcanic field, spewed ash and lava over the land and into the basin. Many of the volcanoes were phreatomagmatic, when ground or lake-water mingled with eruptive material (magma) to cause explosive eruptions. The resulting ash formed fine-grained deposits that were deposited within the lake sediments.

After a few million years of erosion, most of the Bidahochi Formation has been removed from the park area, leaving volcanic scoria cones and maars (flat-bottom, roughly circular volcanic craters of explosive origin). The vent from one of these maars is exposed on the Painted Desert Rim across the park road to the east of Pintado Point. The Hopi Butte Volcanic Field, which can be seen from the northern overlooks of the park extending northwest, is considered one of the largest concentrations of maar landforms in the world, covering about 965 square miles (2,500 square km). The erosion-resistant lava flows, such as Pilot Rock and the Hopi Buttes, protect the softer lake-bed deposits beneath.

Where the Bidahochi and Chinle Formations make contact is an unconformity. An unconformity represents missing rock layers which in turn represents missing time. It’s like a geology textbook with missing pages. You can tell that a page is missing but you can’t tell what was on them. The Chinle Formation was deposited over 200 million years ago but the Bidahochi Formation is only about 8 million years ago. The contact between the Bidahochi and Chinle Formations represents 192 million years of missing time!

Pleistocene and Holocene Sediments

Pleistocene and Holocene Epoch (1.8 million years ago to present) deposits of windblown sand and alluvium (deposited by flowing water), now cover much of the older formations of the park. At higher elevations in the northern part of the park, 500,000-year-old dunes can be found. Younger dunes, around 10,000 years old, are found in drainage areas that contain sand such as Lithodendron Wash. The youngest dunes are found throughout the park, in all settings, deposited around a thousand years ago. These dune deposits are largely stabilized by vegetation, especially grasses. While not as numerous as the fossils of the Chinle Formation, fossils have been found even in the quaternary sediments, including fragments of an ancestral proboscidean (elephants and their relatives, such as mammoths). The Little Colorado River and its tributaries, including the Puerco River, have cut their own valleys into the soft Chinle and Bidahochi Formations of the Painted Desert.

Petrified Forest National Park - Painted Desert - Anthropology

The ancient people may not have recognized the petrified wood as fossil tree pieces, but they did have stories to explain this abundant resource. The Paiute of southern Utah believed the petrified logs to be the arrow shafts of their thunder god, Shinuav. The Navajo believed that the logs were the bones of the monster Yietso, the Great Giant their ancestors slew when they first arrived in the Southwest.

Archeologists use building sites, including the architectural styles, methods, and materials, and associated artifacts, such as pottery and tools, to learn about past human use of the Petrified Forest. Styles evolve and change as ideas spread from place to place. By studying patterns of movement in association with patterns of change, scientists learn about the culture of the prehistoric inhabitants.

Early inhabitants used mostly local materials for dwellings, pottery, tools, clothing, and food, but traded for exotic materials such as turquoise, coral, and shell. Petrified wood may have been an excellent trade item, as evidenced by petrified wood tools found in other areas of the Southwest.

Prehistoric peoples were directly influenced by environmental changes. Ancient storage facilities have been found at some of the habitation sites in the park, indicating that during years when crops were good, they may have stored surpluses just as modern Puebloan people do today.

During the thirteenth century a series of droughts devastated the Southwest. Vegetation decreased and animals died. Farming became impossible in many areas. People migrated or perished. At Petrified Forest it appears that inhabitants congregated into larger pueblos in areas where farming was still a possibility, such as along the Puerco River. By developing new farming methods, new styles of construction, and new customs the people of Puerco Pueblo survived the drought years, only to be forced out by additional environmental change.

Even though several artifacts found in the park represent a human presence in the area over 10,000 years ago, the oldest habitation site may have been occupied just prior to A.D. 500 during the Basketmaker II period. The village had 25 round to oval pithouses scattered about a mesa top, with long, narrow east-facing entryways. They had been dug into the ground and lined with thin slabs of sandstone set on edge. The upper portion of the walls and roof may have been made of brush and mud supported by juniper logs.

Artifacts found at this site include grinding stones, hammerstones, pipes, blades, scrapers, and projectile points. Most of the stone artifacts were made of local materials such as sandstone, chert, and petrified wood. Pottery found includes bowls, jars, ladles, and a vessel in the shape of a duck. Most of the pottery was gray-brown or tan to light red and was left undecorated. Pottery is an important find at such an old site.

Archeologists believe this site was only occupied for part of the year, most likely only during the summer growing season.

A somewhat later site indicates cultural change. Located on the floor of a broad valley, a Basketmaker III site, occupied from about A.D. 500 to A.D. 800, had 15 separate units scattered over almost one-half mile square. Within each unit, the pithouses were deeper and included several semi-subterranean storage structures, usually arranged in a crescent behind the pithouses. One of the houses excavated had mud-plastered walls while another had only the sandstone slab walls as in the Basketmaker II site. Other innovations were small storage pits in the floor and a ventilator shaft.

Cultural change is also shown in the styles of pottery, jewelry, and tools found. The style of projectile points changed and some of the pottery was decorated. Pottery from the Mogollon people to the south and shells of marine origin indicates that trade occurred. Artifacts such as shell and bone awls, needles, pendants, beads, and bracelets were also found.

Human burial sites were found in the village, with evidence that the people had ceremonial burial practices. Even without evidence of any source of water other than summer rainfall, farming must have been productive enough to support a year-round occupation. Low stone windbreaks, farmland on hillsides, the large food-storage structures, and the close-knit organization of the village support occupation all year.

Petrified Forest National Park - Painted Desert - Paleontology

Fossils are clues to the past, allowing researchers to reconstruct ancient animals and plants. Together with the surrounding rocks, fossils tell the stories of ancient ecosystems.

Petrified Forest has plant and animal fossils representing the Late Triassic, going back over 200 million years. The Triassic Period is sometimes referred to as the "Dawn of the Dinosaurs" because it is the time before the Jurassic Period when dinosaurs ruled the earth.

Fossils can be big - some petrified logs found in the park measure over 190 feet - or small - a single tooth less than an inch long may contain the definitive characteristic of a new species.

Every fossil found is like a piece in a jigsaw puzzle. Imagine putting together a jigsaw puzzle without knowing what the completed puzzle will look like. That would be hard, but what if you also didn't have all the pieces?

Context is very important with fossils. Where a fossil is found, what else it is found with, and how it was preserved are clues just as important as the fossil itself. Every fossil found in the park is important because of its context. The context tells its story.

When visiting the park, enjoy the petrified wood, but leave it where you find it. The park loses several tons of petrified wood each year through the acts of thoughtless visitors.

DINOSAURS

Dinosaurs are a rare but important portion of the fossil fauna of Petrified Forest National Park. Park sediments preserve fossils of the Late Triassic "dawn" of the dinosaurs when these animals first appeared worldwide. In contrast to the large sauropods, horned dinosaurs, and the famed Tyrannosaurus rex of the later Jurassic and Cretaceous periods, the Triassic dinosaurs of Arizona were mainly small, bipedal carnivores no bigger than a human in size. Unlike their descendents which filled every terrestrial ecological niche, the dinosaurs of the Triassic shared the landscape with other types of predatory reptiles, most notably the crocodile-like phytosaurs and rauisuchians.

In direct competition with these other voracious predators, the small dinosaurs evolved characteristics that would allow them to compete for prey. These evolutionary developments included characters of the pelvis and ankle which allowed the animals to keep their legs straight under their body for a bipedal stance and greater running ability. The front limbs were now free for uses such as grasping prey. Evidence also suggests that these early dinosaurs may have traveled in packs allowing them to bring down larger prey including the large cow-like dicynodont Placerias and even the armored aetosaurs such as Desmatosuchus. It is also very likely that these predators were generalists and scavenged carcasses for food as do many carnivores today.

However, not all of the Triassic dinosaurs were small meat-eaters. The remains of large herbivores called prosauropods have been found in Europe, South Africa, and South America. These longed necked, bulky animals averaged about 20 feet in length. Moving bipedally, or on all fours, these animals mainly ate vegetation. Prosauropods have not been found in Petrified Forest National Park to date, but it is very likely based on their worldwide distribution that they did occur here. Isolated teeth have been assigned to ornithischian dinosaurs, however recent discoveries have shown that these teeth belong to crocodile-like reptiles rather than dinosaurs. Currently there is no evidence of Late Triassic ornithischian dinosaurs from the park.

Most visitors to the park are surprised to hear that dinosaur fossils are actually very rare finds in the park. This rarity is most likely due to aspects of fossil preservation and not due to a scarcity of dinosaurs in the Triassic. These early dinosaurs were small and possessed hollow bones, the same as modern birds. When an animal died its bones were subject to scavenging by other animals as well as exposure to wind and rain, breaking them down before they were buried. As a result small, hollow bones were less likely to be preserved than the bones of larger reptiles with solid bones. However, current research in the park is looking directly at this problem and targeting areas of the correct age and depositional environment that were more likely to preserve dinosaur bones. Due to the success of this methodology, dinosaur material is becoming more common and our knowledge of Triassic dinosaurs in the American Southwest is on the rise.